The Met Commissioner warned suspects not to sleep easily as he made a fresh appeal for information about the racist killing of the 18-year-old A-level student in 1993.

Speaking as Gary Dobson and David Norris were jailed for the murder, Mr Hogan Howe said: "The other people involved in the murder of Stephen Lawrence should not rest easily in their beds. We are still investigating this case."

Dobson, 36, and Norris, 35, were jailed for a total of 29 years today. But police believe there are as many as seven more suspects in the murder. Among them are Neil and Jamie Acourt and Luke Knight, named as prime suspects in the Macpherson report.

But other names also emerged in the Lawrence inquiry as being people "of interest" to the police. During the murder trial friends and associates of Dobson and Norris were named.Danny Caetano and Charlie Martin both featured heavily in a covert police film in Dobson's flat in December 1994.

Martin shared the flat with Dobson where the bug was planted but Caetano was serving a sentence for another stabbing when Stephen died.

Both men were convicted of trying to "skin a rival alive" at a caravan park in Rochester. Martin received eight years for attempted murder and Caetano was sentenced to four years.

Bradley and Scott Lamb "were both named as suspects on 4 May, 1993" according to Macpherson. They were half-brothers of the Acourts and lived at the Acourts' house on the Brook estate. Scott told police he returned to the house at 11pm on the night of the murder. Bradley was never interviewed by police.

Blue Stuart is described by Macpherson as "both a relative and associate of the Acourts". He was named as a suspect by an informant to a police officer.

The key suspects were investigated in a 1999 police probe which spared no expense in its pursuit of the men.

The Yard bugged homes, cars and workplaces as well as pubs and snooker halls to gather evidence. A house was also purchased in the same street as one suspect and an undercover officer tasked with infiltrating the gang.

Since the 1993 murder a total of 16 suspects have been arrested. Neil Acourt, now 36, who still lives in Eltham, was the leader of the gang and has since changed his surname to Stuart to escape attention. In 2002 he was jailed for 18 months with David Norris for racially abusing a black detective.

His brother Jamie, 34, lives with partner Terri Dean and their young daughter in Sidcup, a few miles from where Stephen Lawrence was killed. He was convicted of stealing empty soda syphons from a drinks warehouse with David Norris.

Luke Knight, 35, was arrested in 1992 with Jamie Acourt and Norris over an alleged stabbing but none was prosecuted. He has been most successful in keeping a low profile and lives with partner Belinda Harmer, 34, in New Eltham.

Former Met chief Lord Blair today called for the wall of silence to be broken over the killers still at large. He said they could be caught if friends or family turn them in.

Q&A

Who are the other suspects?

Police say there are seven other suspects on a list they narrowed down from 187. Witnesses say there were up to six in the gang attack, including a "blond haired boy" who has never been traced.

Three of the prime suspects are Neil and Jamie Acourt and Luke Knight, but other names emerged in the trial and appeared in the Macpherson report.

Will police now arrest other suspects?

Detectives say no new evidence has emerged in the trial which could lead to charges. Their hopes rest largely on the remote prospect of a suspect, possibly Gary Dobson, or a girlfriend turning informant or a new DNA technique discovering fresh forensic evidence.

Can gang leader Neil Acourt be arrested for his violent racist comments and brandishing of a knife on the secret police video?

No. The law has been toughened up against inciting racial hatred and knife possession since 1993 but he would have to be charged under the prevailing legislation. Acourt was also acting in his friend Gary Dobson's flat and not in public.

Can David Norris's parents Clifford and Teresa be arrested for perjury for providing their son with a false alibi?

Unlikely. Police rarely act against "nearest and dearest" evidence which turns out to be false. Former drug baron Clifford escaped charges when he was suspected of trying to fix a previous Old Bailey trial of his son for attempted murder.

Can police bring charges over a cache of weapons found at Neil and Jamie Acourt's home when they were arrested?

Again it is too late to take action nearly 19 years after they were discovered. A knife was also said to have been found under the bed of Gary Dobson's then girlfriend - but it is also too late to act on this.